package com.an.map;

import java.util.HashMap;
import java.util.Map;

public class TestMap {

	public static void main(String[] args) {
		Map<String, String> map = new HashMap<>();
		String a = map.get("a");
		if(a == null) {
			a = "123";
			map.put("a", a);
		}
		System.out.println(map);
	}
}

